This invention relates to an opening device and method for detaching fiber tufts from compressed fiber bales such as cotton or cellulose fiber bales or the like. The opening device has rapidly rotating opening (detaching) rollers which have toothed discs or spikes that cooperate with a grate whose grate bars are situated between the detaching discs or spikes. The opening device travels along the top face of the stationary fiber bales and detaches fiber tufts therefrom.
In a known opening device the parallel axes of the opening rollers are in horizontal alignment with one another. During the forward and return pass the opening rollers penetrate the upper surface of the fiber bale to an equal depth during the detaching operation. The opening rollers rotate in opposite directions such that in the zone of the fiber bales the circumferential part of the opening rollers move towards one another. It is a disadvantage of prior art constructions that as the detaching rollers travel in a given direction during the detaching operation, the two opening rollers detach different quantities of fiber tufts from the fiber bales (one opening roller rotates in the direction of travel and the other rotates oppositely thereto).